Direction finding system



8C. 27, D' I DIRECTION FINDING SYSTEM Filed April 18, 1929 INVENTOR.

A TTORNEY marries starts Patented Dec. 27, 1932 LdtZdSt seranreeeteena'wzannon A. HYLAND, or wesnrne'ron, nrs'rnrcr or 'ocnnnnra, Assrenonr0 WIRED nAnIo, ING., or new YORK, n. 1., n conrona'rronor DELAWAREDIRECTED? FINDING- SYSTEIi/I Application filed April 18,

My invention relates broadly to direction finding systems, and morespecifically to antenna arrangements for direction finding systems.

One of the objects of my invention is to provide an antenna system inwhich a plurality of antennae are interconnected and cooperate toimpress signaling energy, induced into the antennae by wave trainstransmitted from one direction, upon the inpu circuitof a translatingdevice.

Another object of my invention is to provide an antenna system in whicha plurality of interconnected antennae cooperate together to impresssignaling energy received from one or more determinable directions uponthe circuits associated with an observing device. Still another objectof my invention is to provide an antenna system which may be employedeither unidirectional or multidirectional reception.

A further object of my invention is to provide an antenna system whichmay be readily converted from a unidirectional to a bidirecti'onalsystem. I

A still further object of my invention is to provide an antenna systemfor use on moving craft for reception of signals and for determining thedirection from which the signals approach the moving craft.

' Other objects of this invention will be apparent to'those skilled inthe art to which the invention pertains from the following specificationand by reference to the accompanying drawing.

A According to this invention an antenna of a substantiallynondirectional type is connected to acircuit arrangement comprising aninherently directional antenna system, a plurality of series connectedcondensers, a couplin g transformer for transferring signaling energyfrom the circuit arrangement to sig nal translating and interpretingdevices and a tuning condenser for tuning the inherently directionalantenna system. The nondirectional antenna is connected to the terminalsof the directional antenna system and terminals of theprimary winding ofthe coupling transformer through the series connected condensers topermit theadj ustment of the phase ieae. Serial no. 356,185.

relation between the currents flowing to oppoi'ite terminals of thedirectional antenna system and the primary winding of the couplingtransformer and thus eliminate or partially eliminate the efi ectsof thesubstantially nondirectional antenna and render the whole antennasystem, which comprises, the nondirectional, as well as thedirectional-antennae, directive in a certain. direction or in certaindirections. 7 A resistance unit is connected into circuit instead of oneof the series connected condensers by means of a simple switchingarrangement, when it is desired to obtain an antennasystem having theconventional. cardioidal signal diagram.

Referring to the drawing, the sole figure illustrates a circuit diagramembodying a form of this invention.

In the drawing reference numeral 1 designates a vertical or horizontalantenna having substantially nondirectional characteristics. A variablecondenser 2 and a switch 5 are connected tothe antenna 1. A variableresistance unit 4 'anda variable condenser 3 are connected to contactpointsof the switch 5.. A directional antenna, comprising the sections 6and 7 which may be separate loop antennae positioned adjacent to eachother or portions of a split loop antenna,,is connected across theprimary winding 9 of the coupling transformer. 10. A ground connection12 comprising a connection to the metal framework of an aircraft, shipor land vehicle upon which this system is employed, is provided at theelectrical center or approximate electrical center of primary winding 9.Where the sys tem of my invention is employed in permanent landinstallations, such as aircraft landing fields, any conventional groundconnection may be employed. A condenser 8 is connected between sections6 and 7 of the directional antenna and is employed for tuning thecircuit of the directional antenna. The input circuit of an electrondischarge device 13 is connected to the secondary winding 11 of thetransformer 10. A coupling transformer 1 is connected between the outputcircuit of the device 13 and the input circuit of the device 16.

A tuning element 15 is connected into the input circuit of device 16 andan observing device 17 which may consist of-a telephone receivingdevice, a vibrating reed indicating instrument or any other deviceadapted for observing signaling energy. Any type of receiving set may beemployed in conjunction with the antenna system herein described inplace of the receiving set 18.

WVhen it is desired to employ an antenna system having a bilateralsignalresponse characteristic for the reception of signals from oppositedirections, the directional antenna is oriented so that signals which itis desired to receive are received with, a minimum intensity. Thecondensers 2 and 3 are then adjusted until the nondirectional antennacurrents are balanced outas is indicated, usually by a further reductionin the signal as observed through the operation of device 17 Thedirectional antenna comprising sections 6 and 7 is then oriented so thatthe observed signal is substantially zero and in this position the planeof the directional antenna will be perpendicular to the direction of theline of approach of the signal. It the directional antenna is rotated tothe position of maximum signal strength the plane of the directionalantenna will be in line with the direction of approach of the signals.When it is desired to obtain the heart shaped orcardioidalsignalresponse characteristic in the antenna system and thus determine thesense of direction, the resistance 4 is connected into circuit by meansof the switch 5.

The capacity 2 is preferably left constant at the value employed whenthe antenna system was used as a bilateral system and the variableresistance unit 4 is varied to obtain the desiredphase shift between thecurrents flowing'to the terminals of the winding 9.

In employing the antenna system as a unilatera-lor unidirectional systemit is not desirable to eliminate the total efiect of the antenna 1, andthe resistance unit 4: is adjusted accordingly until the maximumresponse is obtainedfrom signals approaching from one direction.capacities 2, 3 and 8 and the resistanceunit 4e are adjusted for anywave length the system may be employed either in unilateral or bilateralreception by manipulating the switch 5 and connecting either theresistance unit 4:, which is preferably noninductive, or the capacity 3into circuit.

While I have described my invention in one of its preferred embodiments,I desire it to be understood that other modifications thereof may bemade and that no limitations upon this invention are intended other thanare imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows: I

1. In a direction finding system, the cornbination'of an antenna havinga substan- Once the values a of tially nondirectional characteristic, adirec-- tlonal antenna, said directional antenna com-. J j prising aplurality of sections, a condenser connected to said sections fortuning, said directional antenna a' condenser connected be:

tween said nondirectional antenna and one of one of the sections of saiddirectional antenna and said nondirectional antenna, and a 0011- plingdevice associated with the circuitsj of said antennae for transferringenergy there- I from. i

2. In a direction finding system, 3;.dll80 tional antenna 'comprising 'apair of sections a tuned circuit interconnecting saidpair, of

sections, a non-directional antenna, a balance; mg condenser connectedbetween said nondirectional antennafand one of the;

of said directional antenna, a second balanqing condenser, a resistor, aswitchfa circuitconnecting said non directional antenna to the other ofsaid sections of said directional antenna through said switch wherebyeither said resistor or said second balancing con:

denser may be selectively connectedin Said. last mentioned c1rcu1t,asignal receivingcit cuit'and means connecting said signal receivingcircuit across the sections; of said'dired tional antenna.

3;In a direction finding systemfa directional antenna comprising apairiof sections-,ja

tuned circuit connecting'said sections in series,

a non directional antenna, a balancing condenser connected between saidnon-d1rect1on-- al' antenna and one of the sections of said directionalantenna, a second balancingcon-fi denser, a variable resistor, aswitch,a. circuit connecting said non-directional antenna to theother of saidsections ofsaiddirectional antenna through said switch whereby eithersaid'resistor or said second balancing con.- f denser may beselectivelyfconnected: in said' lastmentioned circuit, a signalreceiving ci rcuit and coupling means interconnecting said I i circuitand the terminals ofsaiddirectional antenna. r

4. In a direction finding system, a directional antenna comprisinga-pair ofsections, a tuned circuit connecting said sections-in series, anon-directional antenna, a balancing condenser connected between saidnondirec tional antenna and one of the sections of said directionalantenna, a second balancing con denser, a resistor, a switch, acircuit-connecting said non-directional antenna-to the other of saidsections of said d1rectional antenna through said switch whereby eithersaid tosistor or said second balancing condenser may be selectivelyconnected in said last 'mentioned circuit, an output circuit connectedacross said directional antenna, a ground connection approximately atthe electrical midpoint of said output circuit and a receiving circuitconnected with said output circuit, said 5 antenna system beingselectively connected to impart a unilateral or a bilateralcharacteristic to said receiving circuit.

5. In a direction finding system, a directional antenna comprising apair of sections, a tuned circuit connecting said sections in series, anon-directional antenna,a balancing condenser connected between saidnon-directional antenna and one of the sections of said directionalantenna, a second balancing condenser, a resistor, a switch, a circuitconnecting said non-directional antenna to the other of said sections ofsaid directional antenna through said switch whereby either saidresistor or said second balancing condenser may be selectively connectedin said last mentioned circuit, an output circuit connected to saiddirectional antenna, and a signal responsive system connected inelectrical relation with said output circuit, whereby when said switchis connected to said second balancing condenser a true null setting maybe obtained and when said switch is connected to said resistor a truepointing minimum setting may be obtained. LAWRENCE A. HYLAND.

